Gas supply device, substrate processing apparatus and substrate processing method

ABSTRACT

A gas supply mechanism includes a gas introduction member having gas inlet portions through which a gas is introduced into a processing chamber, a processing gas supply unit, a processing gas supply path, branch paths, an additional gas supply unit and an additional gas supply path. The gas inlet portions includes inner gas inlet portions for supplying the gas toward a region where a target substrate is positioned in the chamber and an outer gas inlet portion for introducing the gas toward a region outside an outermost periphery of the target substrate. The branch paths are connected to the inner gas inlet portions, and the additional gas supply path is connected to the outer gas inlet portion.

FIELD OF THE INVENTION

The present invention relates to a gas supply device for supplying a gasinto a processing chamber when a substrate is subjected to a substrateprocessing such as plasma etching or the like, a substrate processingapparatus including the gas supply device and a substrate processingmethod.

BACKGROUND OF THE INVENTION

In a manufacturing process of electronic devices such as semiconductordevices and liquid crystal displays, a substrate processing, e.g.,film-forming processing for forming a predetermined film on the surfaceof a substrate or an etching processing for forming specific patterns toa film formed on a substrate is performed.

In the substrate processing, a plasma is used to obtain high reactivity.In particular, a plasma etching apparatus is frequently used in theetching processing. The plasma etching apparatus includes a processingchamber having a substrate therein, a lower electrode provided in theprocessing chamber for mounting the substrate thereon and an upperelectrode provided in the processing chamber to face with the lowerelectrode, the upper electrode forming a shower head for injecting a gastoward the substrate mounted on the lower electrode. In this plasmaetching apparatus, a specific gaseous mixture is injected through theshower head and a high frequency electric field is formed between thelower and upper electrodes to generate a plasma. The film formed on thesubstrate is etched by the plasma.

In the plasma etching apparatus, the etching characteristics such as anetching rate and an etching selectivity are affected by theconcentration of the gas supplied onto the substrate. In an effort tomake the etching characteristics uniform in the substrate plane, therehave been proposed various methods for adjusting the gas distribution inthe substrate plane.

For example, Japanese Patent Laid-open Publication No. 2006-165399(JP2006-165399A) discloses a technique in which the gas distribution isadjusted by supplying an arbitrary gaseous mixture to a plurality oflocations in a processing chamber with a relatively simple lineconfiguration. Japanese Patent Laid-open Publication No. 2007-207808(JP2007-207808A) discloses a technique in which the gas distribution isadjusted by supplying an arbitrary gaseous mixture to a plurality oflocations in a processing chamber with a simple line configuration andthrough a simple control operation, wherein a processing gas is split toflow through first and second paths so that it can be injected fromfirst and second portions of a shower head, respectively. Further, aspecific additional gas is allowed to flow through these paths, therebyadjusting the ingredient and flow rate of the processing gas. JapanesePatent Laid-open Publication No. 2007-214295 (JP2007-214295A) disclosesa technique in which the gas distribution is adjusted by supplying anarbitrary gaseous mixture to a plurality of locations in a processingchamber with a simple line configuration and through a simple controloperation, wherein a processing gas is split to flow through first andsecond paths so that it can be injected from first and second portionsof a shower head. Independently of the processing gas, a specificadditional gas is injected to thereby adjust the ingredient and flowrate of the processing gas with an increased degree of freedom.

However, requirements for in-plane uniformity of the substrate becomemore and more strict. In particular, it is difficult to correct thecharacteristics of an outermost circumference of a peripheral edge ofthe substrate. Therefore, it sometimes happens that the in-planeuniformity is not sufficiently secured by merely employing thetechniques mentioned above. Further, there happens sometimes that theadditional gas is not needed depending on the process. In case where anadditional gas line is separately provided as in JP2007-214295A, thereis a possibility that, if the additional gas is not supplied, a depositmay be accumulated in injection holes through which the additional gasis to be injected and an abnormal electric discharge may be generated inthe vicinities of the injection holes.

SUMMARY OF THE INVENTION

In view of the above, it is an object of the present invention toprovide a gas supply device capable of effectively correcting thecharacteristics of an outermost circumference of a substrate whileemploying a simple line configuration.

Another object of the present invention is to provide a substrateprocessing apparatus and a substrate processing method capable ofperforming uniform in-plane processing to a substrate by effectivelycorrecting the characteristics of an outermost circumference of thesubstrate.

Still another object of the present invention is to provide a gas supplydevice, a substrate processing apparatus and a substrate processingmethod, each of which is capable of supplying an additional gas inaddition to a processing gas and each of which seldom generates adeposit and an abnormal electric discharge even when the additional gasis not supplied.

In accordance with a first aspect of the present invention, there isprovided a gas supply mechanism for supplying a gas into a processingchamber in which a target substrate is arranged.

The gas supply mechanism includes a gas introduction member provided inthe processing chamber to face with the target substrate, the gasintroduction member having gas inlet portions through which a gas isintroduced into the processing chamber; a processing gas supply unit forsupplying a processing gas into the gas introduction member, theprocessing gas being used for processing the target substrate; aprocessing gas supply path through which the processing gas flows fromthe processing gas supply unit; branch paths for supplying theprocessing gas in a specific split flow rate ratio, the branch pathsbeing branched off from the processing gas supply path and connected tothe gas introduction member; an additional gas supply unit for supplyingan additional gas into the gas introduction member, the additional gasbeing used in adjusting processing characteristics of the processinggas; and an additional gas supply path connected to the additional gassupply unit and the gas introduction member.

The gas inlet portions include inner gas inlet portions for supplying agas toward a region where the target substrate is positioned and anouter gas inlet portion for introducing a gas toward a region outside anoutermost periphery of the target substrate, branch paths beingconnected to inner gas inlet portions, and the additional gas supplypath being connected to the outer gas inlet portion.

In accordance with the first aspect, the gas inlet portions of the gasintroduction member are preferably provided in a concentric pattern. Theouter gas inlet portion is arranged in an outermost position, and innergas inlet portions are arranged inside the outer gas inlet portion.

Further, the gas introduction member may form a shower head having aninternal gas diffusion space and a bottom having gas injection holes,the gas diffusion space being divided into gas diffusion rooms tocorrespond to the gas inlet portions.

Furthermore, the gas inlet portions may include a first gas inletportion for introducing the processing gas toward a central region ofthe target substrate, a second gas inlet portion for introducing theprocessing gas toward a peripheral region of the target substrate, and athird gas inlet portion arranged outside the second gas inlet portion,the first and the second gas inlet portion serve as the inner gas inletportions and the third gas inlet portion serves as the outer gas inletportion.

The branch paths may include a first branch path and a second branchpath respectively connected to the first and the second gas inletportion.

The gas supply mechanism may further includes a switching mechanismcapable of selectively supplying the additional gas and the processinggas to the outer gas inlet portion.

The switching mechanism preferably includes a bypass line connecting theadditional gas supply path to either the processing gas supply path orone of the branch paths and a bypass valve for selectively connectingthe outer gas inlet portion to either the additional gas supply path orthe bypass line.

In accordance with a second aspect of the present invention, there isprovided a gas supply mechanism for supplying a gas into a processingchamber in which a target substrate is arranged. The gas supplymechanism includes a processing gas supply unit for supplying aprocessing gas into the processing chamber, the processing gas beingused in processing the target substrate; one or more processing gasinlet portions through which the processing gas is introduced into theprocessing chamber; a processing gas supply path through which theprocessing gas is supplied from the processing gas supply unit to theprocessing gas inlet portion; and an additional gas supply unit forsupplying an additional gas into the processing chamber.

The gas supply mechanism further includes the additional gas being usedin adjusting processing characteristics of the processing gas; anadditional gas inlet portion through which a gas is introduced into theprocessing chamber; an additional gas supply path through which theadditional gas is supplied from the additional gas supply unit to theadditional gas inlet portion; and a switching mechanism for allowing theprocessing gas to flow through the additional gas inlet portion in casewhere the additional gas is not introduced into the processing chamber.

In accordance with the second aspect, the switching mechanism preferablyincludes a bypass line connecting the additional gas supply path and theprocessing gas supply path and a bypass valve for selectively connectingthe additional gas inlet portion to either the additional gas supplypath or the bypass line.

In accordance with the second aspect, the processing gas supply pathpreferably includes a main path extending from the processing gas supplyunit and branch paths branched off from the main path, the number of theprocessing gas inlet portions being greater than one to correspond withthe branch paths.

In this case, the processing gas inlet portions and the additional gasinlet portion preferably form a gas introduction member provided insidethe processing chamber to face with the target substrate.

The gas introduction member preferably constitutes a shower head havingan internal gas diffusion space and a bottom having gas injection holes,the gas diffusion space being divided into gas diffusion rooms tocorrespond to the processing gas inlet portions and the additional gasinlet portion.

Further, the processing gas inlet portions preferably includes a firstgas inlet portion for introducing the processing gas toward a centralregion of the target substrate and a second gas inlet portion forintroducing the processing gas toward a peripheral region of the targetsubstrate, the additional gas inlet portion being arranged outside thesecond gas inlet portion and supplying the additional or the processinggas toward a region outside an outermost periphery of the targetsubstrate.

In accordance with the first and the second aspect, the additional gasmay differ from the processing gas. The processing gas preferablyincludes plural gases, the additional gas differing from the gases orbeing a part of the gases which form the processing gas.

In accordance with a third aspect of the present invention, there isprovided a substrate processing apparatus including a processing chamberin which a target substrate is arranged, and a gas supply mechanism forsupplying a gas into the processing chamber, wherein a processing gasused for processing the target substrate is supplied from the gas supplymechanism into the processing chamber to perform a specific processingonto the target substrate.

The gas supply mechanism includes a gas introduction member provided inthe processing chamber to be faced with the target substrate, the gasintroduction member having gas inlet portions through which a gas isintroduced into the processing chamber; a processing gas supply unit forsupplying the processing gas into the gas introduction member; aprocessing gas supply path through which the processing gas flows fromthe processing gas supply unit; and branch paths for supplying theprocessing gas in a specific split flow rate ratio.

The gas supply mechanism further includes the branch paths branched offfrom the processing gas supply path and connected to the plurality ofgas inlet portions of the gas introduction member; an additional gassupply unit for supplying an additional gas into the gas introductionmember, the additional gas being used in adjusting processingcharacteristics of the processing gas; and an additional gas supply paththrough which the additional gas flows from the additional gas supplyunit, the additional gas supply path connected to the gas introductionmember.

The gas introduction member includes an outer gas inlet portion forintroducing a gas toward a region outside an outermost periphery of thetarget substrate, and the additional gas supply path being connected tothe outer gas inlet portion.

In accordance with a fourth aspect of the present invention, there isprovided a substrate processing apparatus including a processing chamberin which a target substrate is arranged, and a gas supply mechanism forsupplying a gas into the processing chamber, wherein a processing gasused in processing the target substrate is supplied from the gas supplymechanism into the processing chamber to perform a specific processingonto the target substrate.

The gas supply mechanism includes a processing gas supply unit forsupplying the processing gas into the processing chamber, the processinggas being used for processing the target substrate; one or moreprocessing gas inlet portions through which the processing gas isintroduced into the processing chamber; a processing gas supply paththrough which the processing gas is supplied from the processing gassupply unit to the processing gas inlet portion; an additional gassupply unit for supplying an additional gas into the processing chamber,the additional gas being used in adjusting processing characteristics ofthe processing gas; and an additional gas inlet portion through which agas is introduced into the processing chamber.

The gas supply mechanism further includes an additional gas supply paththrough which the additional gas is supplied from the additional gassupply unit to the additional gas inlet portion; and a switchingmechanism for allowing the processing gas to flow through the additionalgas inlet portion in case where the additional gas is not introducedinto the processing chamber.

In accordance with the third and the fourth aspect, the substrateprocessing apparatus may further includes a plasma generation mechanismfor generating a plasma of the processing gas and the additional gas toprocess the target substrate with the plasma thus generated.

In accordance with a fifth aspect of the present invention, there isprovided a substrate processing method for performing a specificprocessing on a target substrate by introducing a processing gas into aprocessing chamber in which the target substrate is arranged. Thesubstrate processing method further includes supplying the processinggas in a specific split flow rate ratio from portions toward a regionwhere the target substrate is positioned; and supplying an additionalgas, used for adjusting processing characteristics of the processinggas, from an outer portion outside the portions to a region outside anoutermost periphery of the target substrate.

In accordance with the fifth aspect, the portions are provided in aconcentric pattern, the outermost peripheral region being concentricallyarranged outside the portions. In this case, the portions include afirst portion corresponding to a central region of the target substrateand a second region corresponding to a peripheral region of the targetsubstrate.

Further, in accordance with the fifth aspect of the present invention,the specific processing preferably includes plasma processing forplasma-etching a film formed on the target substrate. In case where areaction product is decreased in an outermost periphery region of thetarget substrate in the processing chamber, the additional gas may a gasincluding an ingredient for generating the reaction product.

Furthermore, in case where an ingredient of a film to be etched isdecreased in an outermost periphery region of the target substratewithin the processing chamber, the additional gas may include a gas forgenerating the ingredient of the film.

In accordance with the sixth aspect of the present invention, there isprovided a substrate processing method for performing a specificprocessing on a target substrate by introducing a processing gas into aprocessing chamber in which the target substrate is arranged.

The method includes: processing the target substrate by introducing theprocessing gas from a processing gas inlet portion into the processingchamber toward a region where the target substrate is positioned and byintroducing an additional gas, used for adjusting processingcharacteristics of the processing gas, from an additional gas inletportion into the processing chamber; and processing the target substrateby introducing the processing gas from the processing gas inlet portioninto the processing chamber toward the region where the target substrateis positioned, without introducing the additional gas into theprocessing chamber.

The processing onto the target substrate without introducing theadditional gas into the processing chamber is performed while supplyingthe processing gas via the additional gas inlet portion.

In the present invention, the gas introduction member provided in theprocessing chamber includes a plurality of inner gas inlet portions andan outer gas inlet portion. The processing gas is supplied from theplurality of inner gas inlet portions to the target substratearrangement region in a controlled split flow rate ratio. The additionalgas for adjusting the processing characteristics of the processing gasis allowed to flow from the outer gas inlet portion to the regionoutside the outermost periphery of the target substrate. These featuresmake it possible to efficiently correct and optimize the processingcharacteristics in the outermost circumferential region of the targetsubstrate, thus making the processing characteristics more uniform. Inother words, it is difficult to correct the processing characteristicsof the outermost circumferential region of the target substrate eventhough the additional gas is supplied to the edge region of the targetsubstrate. However, if the additional gas is supplied to the regionoutside the outermost periphery of the target substrate, the additionalgas acts effectively on the outermost circumferential region of thetarget substrate. This makes it possible to correct the processingcharacteristics of the outermost circumferential region.

Furthermore, the present gas supply device is provided with theprocessing gas inlet portion for introducing the processing gas into theprocessing chamber and the additional gas inlet portion for introducingthe additional gas into the processing chamber, so that the processinggas and the additional gas can be supplied to the target substrate. Thegas supply device is further provided with the switching mechanism forswitching, when the additional gas is not introduced into the processingchamber, the path in such a manner as to allow the processing gas toflow through the additional gas inlet portion. These features allow theprocessing gas to flow through the additional gas inlet portion in caseof not introducing the additional gas. This makes it possible toeliminate the possibility that no gas flows through the gas injectionholes of the additional gas inlet portion during the course ofprocessing. As a consequence, it is possible to avoid generation of adeposit in the gas injection holes of the additional gas inlet portion.In case of plasma processing, it is possible to prevent an abnormalelectric discharge from being generated in the gas injection holes.

BRIEF DESCRIPTION OF THE DRAWINGS

The objects and features of the present invention will become apparentfrom the following description of embodiments, given in conjunction withthe accompanying drawings, in which:

FIG. 1 is a schematic cross sectional view showing a plasma etchingapparatus as a substrate processing apparatus to which a gas supplydevice is applied in accordance with one embodiment of the presentinvention;

FIG. 2 is a bottom plan view showing a shower head employed in theplasma etching apparatus shown in FIG. 1;

FIG. 3 is a pattern diagram illustrating a configuration of a gas supplydevice installed in the plasma etching apparatus shown in FIG. 1;

FIGS. 4A through 4D are views diagrammatically illustrating examples ofetching characteristics corrected by the plasma etching apparatus shownin FIG. 1;

FIG. 5 shows scanning electron micrographs illustrating a status ofetching patterns in a central region and a peripheral region in casewhere a SiN film is etched by the plasma etching apparatus shown in FIG.1 without using an additional gas;

FIGS. 6A and 6B are views illustrating critical dimension shift amountsin a dense pattern portion and an isolative pattern portion along aradial direction of a wafer in case where a SiN film is etched by theplasma etching apparatus shown in FIG. 1 without using an additionalgas;

FIG. 7 is a view illustrating results of simulation for a concentrationdistribution of a CN-based material as a reaction product in case wherea SiN film is etched by the plasma etching apparatus shown in FIG. 1without using an additional gas;

FIGS. 8A and 8B are views illustrating critical dimension shift amountsin a dense pattern portion and an isolative pattern portion along aradial direction of a wafer in case where a SiN film is etched by theplasma etching apparatus shown in FIG. 1 with a CH₂F₂ gas used as anadditional gas;

FIGS. 9A and 9B are views illustrating selectivity shift amounts along aradial direction of a wafer in case where a CH₂F₂ gas as an additionalgas is supplied to an edge portion of a wafer and to a region outsidethe outermost periphery of the wafer when a SiN film is etched by theplasma etching apparatus shown in FIG. 1;

FIG. 10 is a view illustrating one example of a sample structure used inactually making the etching characteristics uniform in accordance withthe present invention;

FIG. 11 is a view illustrating another example of a sample structureused in actually making the etching characteristics uniform inaccordance with the present invention; and

FIG. 12 is a view illustrating a further example of a sample structureused in actually making the etching characteristics uniform inaccordance with the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Hereinafter, an embodiment of the present invention will be describedwith reference to the accompanying drawings which form a part hereof.FIG. 1 is a schematic cross sectional view showing a plasma etchingapparatus as a substrate processing apparatus to which a gas supplydevice is applied in accordance with an embodiment of the presentinvention. FIG. 2 is a bottom plan view showing a shower head employedin the plasma etching apparatus shown in FIG. 1.

The plasma etching apparatus is a capacitively coupled parallel platetype plasma etching apparatus. The plasma etching apparatus includes asubstantially cylindrical airtight chamber 1 of which wall is formed of,e.g., an aluminum material having an oxidized surface. The chamber 1 iselectrically grounded.

In the chamber 1, there is provided a support table 2 for horizontallysupporting a semiconductor wafer (hereinafter simply referred to as a“wafer”) W as a target substrate to be processed, the support table 2serving as a lower electrode. The support table 2 is formed of, e.g., analuminum material having an oxidized surface and is supported via aninsulation member 4 on a support base 3 extending upward from a bottomportion of the chamber 1. A focus ring 5 made of a conductive materialor an insulating material is provided on an outermost periphery of thesupport table 2. A baffle plate 14 is provided outside the focus ring 5.A cavity 7 is formed between the support table 2 and the bottom portionof the chamber 1.

On the surface of the support table 2, there is provided anelectrostatic chuck 6 for electrostatically attracting the wafer W. Theelectrostatic chuck 6 is formed of an electrode 6 a interposed betweeninsulation bodies 6 b. A DC power supply 13 is connected to theelectrode 6 a. As a voltage is applied from the power supply 13 to theelectrode 6 a, the wafer W is attracted to the electrostatic chuck 6 by,e.g., Coulomb force.

A coolant path 8 a is formed in the support table 2 and a coolant line 8b is connected to the coolant path 8 a. Under the control of a coolantcontroller 8, an appropriate coolant is supplied to the coolant path 8 athrough the coolant line 8 b and is circulated through the coolant path8 a and the coolant line 8 b. This makes it possible to control thesupport table 2 to be maintained at a desirable temperature. Alsoprovided is a heat transfer gas line 9 a for supplying a heat transfergas, e.g., a He gas, to a space between the front surface of theelectrostatic chuck 6 and the rear surface of the wafer W. A heattransfer gas supply unit 9 is provided to supply the heat transfer gasto the rear surface of the wafer W via the heat transfer gas line 9 a.This makes it possible to efficiently transfer the cold heat of thecoolant circulating through the coolant path 8 a to the wafer W eventhough the chamber 1 is evacuated and kept vacuum, thereby improving thetemperature control of the wafer W.

A power supply wire 12 for supplying a high frequency power is connectedto a substantially central portion of the support table 2. A matchingbox 11 and a high frequency power supply 10 are connected to the powersupply wire 12. A high frequency power of a specific frequency, e.g.,100 MHz or more, is supplied from the high frequency power supply 10 tothe support table 2. A shower head 16 to be described later is arrangedabove the support table 2 serving as a lower electrode in a parallelfacing relationship therewith. The shower head 16 is electricallygrounded via the chamber 1. Therefore, the shower head 16 serves as anupper electrode and forms a pair of parallel plate electrodes togetherwith the support table 2.

The shower head 16 is engaged to the ceiling wall of the chamber 1. Theshower head 16 includes a first gas inlet portion 51 for introducing agas toward a wafer center region (central region) within the chamber 1,a second gas inlet portion 52 for introducing the gas toward a waferperiphery region (edge region) within the chamber 1 and a third gasinlet portion 53 for introducing the gas toward an outer region than thewafer periphery region. The first, second and third inlet portions 51,52 and 53 are arranged in a concentric relationship with one another.

The shower head (gas introduction member) 16 includes a shower head body16 a and an electrode plate 18 detachably provided on the bottom surfaceof the shower head body 16 a. A plurality of gas injection holes 17 isformed to penetrate the bottom wall of the shower head body 16 a and theelectrode plate 18. A gas diffusion space (internal gas diffusion space)40 is provided in the shower head body 16 a. By means of first andsecond annular partition wall members 42 and 43 each formed with, e.g.,an O-ring, the gas diffusion space 40 is divided into gas diffusionrooms having a first gas diffusion space 40 a positioned centrally, asecond gas diffusion space 40 b lying outside the first space 40 a and athird (outermost) gas diffusion space 40 c lying outside the secondspace 40 b. The plurality of gas injection holes 17 extends downwardlyfrom the first gas diffusion space 40 a, the second gas diffusion space40 b and the third gas diffusion space 40 c. The first gas inlet portion51 is formed with the first gas diffusion space 40 a and a plurality ofgas injection holes 17 arranged just below the first space 40 a. Thesecond gas inlet portion 52 is formed with the second gas diffusionspace 40 b and a plurality of gas injection holes 17 arranged just belowthe second space 40 b. The third gas inlet portion 53 is formed with thethird gas diffusion space 40 c and a plurality of gas injection holes 17arranged just below the third space 40 c.

A processing gas for use in an etching process is supplied into thefirst and second gas diffusion spaces 40 a and 40 b so that it can beinjected toward the wafer W. An additional gas is supplied into thethird gas diffusion space 40 c. The gas injection holes 17 correspondingto the third gas diffusion space 40 c are aligned with the regionoutside the outermost periphery of the wafer W mounted on the supporttable 2 so that the additional gas can be injected toward the regionoutside the outermost periphery of the wafer W.

A common processing gas supply unit 66 is designed to supply theprocessing gas into the first and second gas diffusion spaces 40 a and40 b in a desired flow rate ratio. More specifically, a gas supply line(main path) 64 extends from the processing gas supply unit 66 and isbifurcated into two branch lines (branch paths) 64 a and 64 b which inturn are connected to gas inlet openings 62 a and 62 b formed at theshower head body 16 a. The processing gas passing through the gas inletopenings 62 a and 62 b is led to the first and second gas diffusionspaces 40 a and 40 b. The branch flow rate of the processing gas flowingthrough the branch lines 64 a and 64 b is regulated by means of a branchflow controller 71 provided somewhere along the branch lines 64 a and 64b.

An additional gas for use in adjusting the etching characteristicsattained by the processing gas is supplied from an additional gas supplyunit 75 into the third gas diffusion space 40 c. The additional gas hasa specific roll of, e.g., assuring uniform etching during an etchingoperation. A gas supply line (additional gas supply path) 76 extendsfrom the additional gas supply unit 75 and is connected to a gas inletopening 62 c formed at the shower head body 16 a. The additional gaspassing through the gas inlet portion port 62 c is led to the third gasdiffusion space 40 c. The shower head 16, the processing gas supply unit66, the additional gas supply unit 75, the branch flow controller 71 andthe piping system cooperate with one another to form a gas supply device(gas supply mechanism) 60.

FIG. 3 is a schematic diagram illustrating a configuration of the gassupply device 60. The processing gas supply unit 66 includes a pluralityof, e.g., three, processing gas sources 67 a, 67 b and 67 c, the numberof which varies depending on the kinds of processing gas used. Gas lines68 a, 68 b and 68 c respectively extend from the processing gas sources67 a, 67 b and 67 c. Mass flow controllers 69 serving as flow ratecontrollers and opening/closing valves 70 are arranged in the gas lines68 a, 68 b and 68 c so that plural kinds of processing gases can berespectively supplied at a desired flow rate. The gas lines 68 a, 68 band 68 c join the gas supply line 64. As a result, a gaseous mixture ofthe plural kinds of processing gases flows through the gas supply line64. The number of the processing gas sources varies with the kinds ofprocessing gases used and may be smaller than or greater than three.

The branch flow controller 71 includes flow rate control valves 71 a and71 b and pressure sensors 72 a and 72 b arranged in the branch lines 64a and 64 b. Since the paths extending from the processing gas supplyunit 66 to the first and second gas diffusion spaces 40 a and 40 b havea same conductance, the flow rate ratio of the processing gases suppliedinto the first and second gas diffusion spaces 40 a and 40 b can becontrolled at will with the flow rate control valves 71 a and 71 b. Theflow rate is actually controlled by adjusting the opening degree of theflow rate control valves 71 a and 71 b based on detection values of thepressure sensors 72 a and 72 b.

The additional gas supply unit 75 includes an additional gas source 77connected to the gas supply line 76, a mass flow controller 78 as a flowrate controller arranged in the gas supply line 76 and a opening/closingvalve 79 also arranged in the gas supply line 76.

By controlling the flow rate ratio of the processing gases introducedinto the first and second gas diffusion spaces 40 a and 40 b asmentioned above, it is possible to arbitrarily adjust the ratio Fc/Fe ofthe flow rate F_(c) of the processing gas introduced from the firstcentral gas inlet portion 51 into the chamber 1 and the flow rate Fe ofthe processing gas introduced from the second peripheral gas inletportion 52 into the chamber 1. This makes it possible to perform radicaldistribution control. Independently of the processing gas, a specificadditional gas may be introduced in a predetermined ratio with respectto the processing gas from the third gas diffusion space 40 c of thethird gas inlet portion 53 toward the region outside the outermostperiphery of the wafer W in the chamber 1.

The gas supply line 76 for supplying the additional gas and the branchline 64 b are connected to each other by a bypass line 80. A switchingvalve (bypass valve) 81 is arranged in the junction point of the gassupply line 76 and the bypass line 80. The switching valve 81 is formedof, e.g., a three-way valve. In case of supplying the additional gas,the switching valve 81 disconnects the third gas diffusion space 40 cfrom the bypass line 80 so that the additional gas can be supplied intothe third gas diffusion space 40 c. In case of the additional gas notbeing supplied, the switching valve 81 disconnects the third gasdiffusion space 40 c from the additional gas supply unit 75 so that theprocessing gas can be supplied into the third gas diffusion space 40 cthrough the bypass line 80. This eliminates the possibility that no gasflows through the gas injection holes 17 corresponding to the third gasdiffusion space 40 c even when the additional gas is not used inprocessing the wafer W.

An exhaust line 19 is connected to the bottom of the chamber 1 and a gasexhaust unit 20 including a vacuum pump is connected to the exhaust line19. The inner space of the chamber 1 can be depressurized to apredetermined vacuum level by operating the vacuum pump of the gasexhaust unit 20. In an upper portion of a sidewall of the chamber 1,there is provided a gate valve 24 for opening and closing aloading/unloading port 23 through which the wafer W is loaded andunloaded.

Two annular magnets 21 a and 21 b are concentrically arranged above andbelow the loading/unloading port 23 of the chamber 1 so that they can berotated around the chamber 1. The magnets 21 a and 21 b form magneticfields around the processing space between the support table 2 and theshower head 16. The magnets 21 a and 21 b can be rotated by a rotatingmechanism not shown in the drawings.

Components of the plasma etching apparatus, e.g., the processing gassupply unit 66, the split flow rate regulating mechanism 71, theadditional gas supply unit 75, the high frequency power source 10, thematching box 11, the direct current source 13, the coolant controller 8,the heat transfer gas supply unit 9 and the exhaust unit 20, areconnected to and controlled by a control unit (process controller) 90which is a microprocessor (computer). Connected to the controller 90 isa user interface 91 that includes a keyboard for a process manager toinput a command to operate the plasma etching apparatus, a display forshowing an operational status of the plasma etching apparatus, and thelike.

Also connected to the controller 90 is a storage unit 92 that storestherein, e.g., control programs to be used in realizing variousprocesses, which are performed in the plasma processing apparatus underthe control of the process controller 90, and/or a program, i.e.,recipes, for making the components of the plasma etching apparatusperform processing tasks in accordance with processing conditions. Therecipes are stored in a storage medium of the storage unit 92. Thestorage medium may be either a stationary one such as a hard disk or thelike or a portable one such as a CDROM, a DVD or the like.Alternatively, the recipes may be suitably transmitted from anotherapparatus via, e.g., a dedicated line. If necessary, an arbitrary one ofthe recipes is called out from the storage unit 92 by inputting aninstruction to that effect through the user interface 91. The controller90 performs the recipe thus called out. Consequently, a desiredprocessing task is carried out in the plasma etching apparatus under thecontrol of the controller 90.

Next, description will be made on the processing operation of the plasmaetching apparatus with the configuration as above. The processingoperation is controlled by the controller 90 described above.

First, the gate valve 24 is opened and the wafer W is loaded into thechamber 1 by using a transfer arm. After the wafer W is mounted on thesupport table 2, the transfer arm is retracted and the gate valve 24 isclosed. The inner space of the chamber 1 is evacuated through theexhaust line 19 to a predetermined vacuum level by using the vacuum pumpof the exhaust unit 20.

Then, a processing gas for an etching operation is supplied from theprocessing gas supply unit 66 to the first gas diffusion space 40 a andthe second gas diffusion space 40 b at a specific flow rate and in aspecific ratio, thereby adjusting the ratio of the processing gassupplied into the first gas inlet portion 51 and the second gas inletportion 52. A specific additional gas is supplied into the third gasdiffusion space 40 c of the third gas inlet portion 53. While supplyingthe processing gas and the additional gas into the chamber 1 through thegas injection holes 17, the chamber 1 is evacuated by the vacuum pump ofthe exhaust unit 20 to set the pressure in the chamber 1 to be within arange from 1 to 150 Pa.

In this regard, various kinds of conventionally available gases may beused as the processing gas. It is preferable to use, e.g., a gasincluding a halogen element, which is represented by a fluorocarbon gas(C_(x)F_(y)) such as a C₄F₈ gas or the like. Other gases such as an Argas and an O₂ gas may be used in combination with or in place of the gasincluding a halogen element.

The additional gas is used to increase the in-plane etching uniformityof the wafer by adjusting the etching environment around the portion ofthe wafer whose etching characteristics are peculiar. For example, it issometimes the case that the linear shape of an etching film in aperipheral edge portion of the wafer becomes thin due to the smallamount of by-product. In this case, it is effective that a gas capableof generating a by-product is supplied as the additional gas. As anotherexample, it is sometimes the case that the linear shape of an etchingfilm in an outermost periphery of the wafer becomes thin due to ashortage of a gas corresponding to a composition ingredient of a film.In this case, it is effective that the gas corresponding to thecomposition ingredient of the film is supplied as the additional gas. Itis possible to use, as the additional gas, either a fraction of theprocessing gas or a gas other than the processing gas.

While the processing gas and the additional gas are introduced into thechamber 1 in this manner, a high frequency power having frequency of 10MHz or more, e.g., 13.56 MHz is supplied from the high frequency powersource 10 to the support table 2. At this time, a predetermined level ofvoltage is applied from the direct current source 13 to the electrode 6a of the electrostatic chuck 6, whereby the wafer W is adsorbed to theelectrostatic chuck 6 by, e.g., Coulomb force.

As the high frequency power is applied to the support table 2 serving asthe lower electrode in the manner as noted above, the high frequencyelectric field is formed in the processing space between the shower head16, i.e., the upper electrode, and the support table 2, i.e., the lowerelectrode. Thus, the processing gas supplied into the processing spaceis turned to a plasma. An etching target film of the wafer W is etchedby radicals or ions present in the plasma.

Depending on the kinds of processing to be performed, it would bepossible to make the etching characteristics uniform by using theradical distribution control in which the flow rate of the processinggas is adjusted differently in the central region and the peripheralregion of the wafer W or by allowing the additional gas to flow towardthe peripheral region of the wafer W, as disclosed in JP2006-165399A,JP2007-207808A and JP2007-214295A mentioned earlier.

However, when etching a SiN film used as a hard mask layer or whenetching an organic film such as an interlayer insulation film having alow dielectric constant, the outermost circumferential portion of thewafer W undergoes a sharp change in its etching characteristics,especially in its critical dimension (CD). More specifically, there is atendency that the resist becomes thin in the outermost circumferentialportion of the wafer W. In this case, the uniform etchingcharacteristics may not be always attained by merely performing theradical distribution control or the additional gas supply with thehardware configurations as described in JP2006-165399A, JP2007-207808Aand JP2007-214295A mentioned earlier.

In the present embodiment, the additional gas is introduced through thethird gas inlet portion 53 toward the position outside the outermostperiphery of the wafer W, in addition to the processing gas flowingthrough the first and second gas introduction portions 51 and 52 in acontrolled flow rate ratio.

These features make it possible to efficiently correct and optimize theetching characteristics in the outermost circumferential portion of thewafer W, thus making the etching characteristics more uniform. In otherwords, it is difficult to correct the etching characteristics of theoutermost circumferential portion of the wafer W even when theadditional gas is supplied to the edge region of the wafer W. However,if the additional gas is supplied to the region outside the outermostperipheral portion of the wafer W, the additional gas acts effectivelyon the outermost peripheral portion of the wafer W. This makes itpossible to correct the etching characteristics of the outermostcircumferential portion.

Although the additional gas may diffuse toward the middle and centralregions of the wafer W and may cause a change in the environment ofthese regions, the influence of the additional gas can be cancelled byadjusting the ratio of the processing gas supplied through the first gasinlet portion 51 and the second gas inlet portion 52.

Such correction of the etching characteristics will be described indetail with reference to FIGS. 4A to 4D. In case where a CH₂F₂ gas, aCF₄ gas, an Ar gas and an O₂ gas are used as the processing gas whilethe additional gas is not used when etching, e.g., a SiN film, theetching critical dimension tends to sharply decrease beyond the middleregion as illustrated in FIG. 4A. In case where a CH₂F₂ gas as theadditional gas is supplied toward the edge region of the wafer Wtogether with the processing gas, the critical dimension distribution isimproved but the critical dimension of the outermost circumferentialportion of the wafer W suffers from reduction, as illustrated in FIG.4B. The critical dimension reduction in that portion is not improvedeven by controlling the spatial distribution of the radical density. Incase where a CH₂F₂ gas as the additional gas is supplied toward theregion outside the outermost peripheral portion of the wafer W as in thepresent embodiment, it becomes possible to optimize the criticaldimension correction effect to the outermost circumferential portion ofthe wafer W as can be seen in FIG. 4C. The critical dimension reductionin the central region of the wafer W appeared in FIG. 4C can bedissolved as illustrated in FIG. 4D by adjusting the ratio of theprocessing gas supplied through the first and second gas introductionportions 51 and 52 and thus controlling the spatial distribution of theradical distribution. This makes it possible to remarkably increase theuniformity in the critical dimension. FIGS. 4A to 4D diagrammaticallyillustrate the general tendency of the change in the etchingcharacteristics (critical dimension).

Depending on the process, there may be no need to use the additionalgas. In this case, if the supply of the additional gas is merelystopped, no gas flows through the gas injection holes 17 correspondingto the third gas diffusion space 40 c. If a plasma is generated in thisstate, the plasma enters the gas injection holes 17 corresponding to thethird gas diffusion space 40 c, thereby generating an abnormal electricdischarge or a deposit in the gas injection holes 17.

In the present embodiment, the gas supply line 76 and the branch line 64b are connected to each other by the bypass line 80. The switching valve81 is employed so that the additional gas and the processing gas can beselectively supplied to the third gas diffusion space 40 c. In casewhere there is no need to supply the additional gas, the switching valve81 is opened to the bypass line 80 so that the processing gas can flowinto the third gas diffusion space 40 c. This makes it possible toprevent the abnormal electric discharge or the deposit.

Next, description will be made on the experimental results that helpedto develop the present invention.

In one experiment, a 300 mm wafer was used, the wafer being obtained bylaminating a SiN film of 200 nm, a polyvinyl alcohol-based resin film of287 nm, an anti-reflection film of 80 nm and a photoresist film in thatorder on a Si substrate and then patterning the photoresist film into acritical dimension (line width) of 80 nm through a photolithographyprocess. The outermost gas injection holes of the shower head 16 werearranged within the wafer arrangement region (up to 140 mm from thecenter). Except the above points, the same plasma etching apparatus asshown in FIG. 1 was used to etch the wafer down to the SiN film. At thistime, a CHF₃ gas, a CF₄ gas, an Ar gas and an ° 2 gas were used as theprocessing gas. The flow rates of the CHF₃, CF₄, Ar and O₂ gases were30, 90, 600 and 15 mL/min (sccm), respectively. The flow rate ratio ofthe processing gas supplied toward the central region to the edge regionwas 45:55. The pressure in the chamber was 16.6 Pa (125 mTorr) and thehigh frequency power was 600 W. Etching was performed under theseconditions. As a result, it was confirmed that the lines existing in theperipheral region became thinner than the lines of the central regionboth for the dense pattern portion and the isolative pattern portion, ascan be seen from the scanning electron micrographs shown in FIG. 5. Inthe respective micrographs shown in FIG. 5, the left numerals signifythe top critical dimension (nm) and the right numerals stand for thebottom critical dimension (nm).

In another experiment, the same plasma etching apparatus as in thepreceding experiment was used. At this time, a CH₂F₂ gas, a CF₄ gas, anAr gas and an O₂ gas were used as the processing gas. The flow rates ofthe CH₂F₂, CF₄, Ar and O₂ gases were 20, 80, 150 and 21 mL/min (sccm),respectively. The flow rate ratio of the processing gas supplied towardthe central region to the edge region was 45:55. The pressure in thechamber was 18.6 Pa (140 mTorr) and the high frequency power was 700 W.Under these conditions, the SiN film was etched to form lines having acritical dimension (line width) of 80 nm. Critical dimension shiftamounts in a dense pattern portion and an isolative pattern portionalong a radial direction of the wafer are illustrated in FIGS. 6A and6B. It can be seen in FIGS. 6A and 6B that the critical dimension isdecreased in the edge portion of the wafer.

Investigation on the indices having something to do with the criticaldimension reduction in the edge portion of the wafer revealed that, asillustrated in FIG. 7, the critical dimension reduction was related tothe concentration of a CN-based material as a reaction product(by-product) and the concentration of the reaction product was decreasedin the edge portion of the wafer. FIG. 7 shows data acquired byconducting a simulation in positions 0.5 mm above the wafer. From theresults illustrated in FIG. 7, it can be speculated that the criticaldimension reduction results from the reduction in the concentration ofthe reaction product (CN-based material) in the wafer edge portion.

In another experiment, a plasma etching apparatus used in theabove-described experiment was used in which the outermost gas injectionholes of the shower head 16 were arranged within the wafer arrangementregion (up to 140 mm from the center). A CH₂F₂ gas as an alternative ofthe CN-based material, i.e., the reaction product, was used as theadditional gas. Simultaneously with supplying the processing gas, theCH₂F₂ gas was injected toward the edge portion of the wafer through theoutermost gas injection holes (corresponding to the second gas diffusionspace 40 b of the plasma etching apparatus shown in FIG. 2). Criticaldimension shift amounts in a dense pattern portion and an isolativepattern portion along a radial direction of the wafer available in thisexperiment are illustrated in FIGS. 8A and 8B. It can be seen in FIGS.8A and 8B that the critical dimension reduction in the outermostcircumferential portion of the wafer remains unsolved, although thecritical dimension reduction in the wafer edge portion is mitigated andthe uniformity of the critical dimension is improved by the additionalgas.

In the present invention, a CH₂F₂ gas as the additional gas was suppliedtoward the region outside the outermost periphery of the wafer (theregion 156 mm away from the center). As a result, it was possible tocorrect the critical dimension reduction which would otherwise occur inthe outermost periphery of the wafer. FIGS. 9A and 9B do not directlyillustrate the critical dimension shift amounts but show shift amountsin the selectivity of the SiN film relative to the resist film, whichhave a strong correlation with the critical dimension shift amounts.

FIG. 9A illustrates the selectivity shift amounts in case where theCH₂F₂ gas as the additional gas was supplied toward the edge portion ofthe wafer, whereas FIG. 9B represents the selectivity shift amounts incase where the CH₂F₂ gas as the additional gas was supplied toward theregion outside the peripheral region of the wafer. In FIG. 9A, theselectivity was decreased in the outermost circumferential region of thewafer. In FIG. 9B, however, the selectivity was increased to a maximumvalue in the outermost circumferential region of the wafer. In thisstate, the etching characteristics can be made uniform by the radicaldistribution control.

The above experiments were directed to a case where the etchingcharacteristics in the wafer edge portion were affected by theconcentration of the reaction product (by-product) present in theetching atmosphere. In some instances, the concentration of ingredientsof a film has an influence on the etching characteristics in the waferedge region. For example, during the process of etching an amorphouscarbon film or an organic film, the concentration of carbon, i.e., oneof the ingredients of the film, is reduced in the atmosphere around thewafer edge region. Consequently, there is a tendency that the criticaldimension is decreased in the wafer edge region. In this case, a gascapable of increasing the concentration of carbon as one of theingredients of the film, e.g., a CO gas, may be used as the additionalgas. Use of such an additional gas helps make the etchingcharacteristics such as the critical dimension and the like uniform.

Next, description will be made on examples in which the etchingcharacteristics were actually made uniform in accordance with thepresent invention.

Referring to FIG. 10, a wafer sample was obtained by laminating a SiNfilm 102 as a hard mask, an anti-reflection film (BARC) 103 and aphotoresist film (PR) 104 in that order on a Si substrate 101 and thenpatterning the photoresist film 104 through a photolithography process.The anti-reflection film 103 and the SiN film 102 were etched by theplasma etching apparatus shown in FIG. 1.

As the common conditions for etching the reflection film 103 and the SiNfilm 102, the wafer was kept at a temperature of 60° C. and the flowrate ratio of the processing gas supplied toward the central region andthe edge region was set to be 45:55. During the process ofplasma-etching the anti-reflection film 103, a CF₄ gas, an Ar gas and anO₂ gas were supplied as the processing gas at the flow rates of 120mL/min (sccm), 420 mL/min (sccm) and 15 mL/min (sccm), respectively. Thepressure in the chamber was set to 13.3 Pa (100 mTorr), and the highfrequency power was set to 800 W. When plasma-etching the SiN film 102,a CH₂F₂ gas, a CF₄ gas, an Ar gas and an O₂ gas were supplied as theprocessing gas at the flow rates of 20 mL/min (sccm), 80 mL/min (sccm),150 mL/min (sccm) and 20 mL/min (sccm), respectively. Further, a CH₂F₂gas capable of generating a CN-based reaction product was supplied asthe additional gas toward the region outside the outer edge of the waferthrough the third gas diffusion space 40 c at the flow rate of 2 mL/min(sccm). The pressure in the chamber was set to 18.6 Pa (140 mTorr), andthe high frequency power was set to 700 W. When plasma-etching theanti-reflection film 103, the processing gas was supplied through thethird gas diffusion space 40 c.

As a result, when etching the SiN film 102, the critical dimension inthe outermost circumferential portion of the wafer was corrected withthe help of the reaction of the CH₂F₂ gas used as the additional gas.Thus, it was possible to perform the etching operation with increaseduniformity. Despite the fact that the additional gas was not suppliedduring the etching of the anti-reflection film 103, neither abnormalelectric discharge nor deposit was generated because the processing gaswas injected from the third gas diffusion space 40 c for use insupplying the additional gas.

Referring next to FIG. 11, a wafer sample was obtained by laminating aSiN film 202 as a hard mask, an amorphous carbon (a-C) film 203, a SiO₂film 204 and a photoresist film (PR) 205 in that order on a Si substrate201 and then patterning the photoresist film 205 through aphotolithography process. The SiO₂ film 204 and the amorphous carbonfilm 203 were etched by the plasma etching apparatus shown in FIG. 1.

As the common conditions for etching the SiO₂ film 204 and the amorphouscarbon film 203, the wafer was kept at a temperature of 20° C. and theflow rate ratio of the processing gas supplied toward the central regionand the edge region was set to 50:50. During the plasma-etching of theSiO₂ film 204, a CF₄ gas was supplied as the processing gas at the flowrate of 150 mL/min (sccm). The pressure in the chamber was set to 10.6Pa (80 mTorr), and the high frequency power was set to 400 W. Whenplasma-etching the amorphous carbon film 203, an O₂ gas and an Ar gaswere supplied as the processing gas at the flow rates of 180 mL/min(sccm) and 300 mL/min (sccm), respectively. Furthermore, a CO gascapable of increasing the film ingredients in the etching atmosphere wassupplied as the additional gas toward the region outside the outermostperipheral region of the wafer through the third gas diffusion space 40c at the flow rate of 200 mL/min (sccm). The pressure within the chamberwas set to 4.0 Pa (30 mTorr), and the high frequency power was set equalto 500 W. When plasma-etching the SiO₂ film 204, the processing gas wassupplied through the third gas diffusion space 40 c.

As a result, when etching the amorphous carbon film 203, the criticaldimension in the outermost circumferential portion of the wafer wascorrected with the help of the reaction of the CO gas as the additionalgas. Thus, it was possible to perform the etching operation withincreased uniformity. Despite the fact that the additional gas was notsupplied during the etching of the SiO₂ film 204, neither abnormalelectric discharge nor deposit was generated because the processing gaswas injected from the third gas diffusion space 40 c for use insupplying the additional gas.

Next, a wafer sample shown in FIG. 12 was obtained by laminating a SiNfilm 302 as a hard mask, a polyvinyl alcohol-based resin film (OPL) 303,an anti-reflection film (Si-ARC) 304 and a photoresist film (PR) 305 inthat order on a Si substrate 301 and then patterning the photoresistfilm 305 through a photolithography process. The anti-reflection film304 and the polyvinyl alcohol-based resin film 303 were etched by theplasma etching apparatus shown in FIG. 1.

As the common conditions for etching the anti-reflection film 304 andthe polyvinyl alcohol-based resin film 303, the wafer was kept at atemperature of 20° C. and the flow rate ratio of the processing gassupplied toward the central region and the edge region was set to 50:50.During the plasma-etching of the anti-reflection film 304, a CF₄ gas wassupplied as the processing gas at the flow rate of 150 mL/min (sccm).The pressure in the chamber was set to 10.6 Pa (80 mTorr), and the highfrequency power was set to 400 W. When plasma-etching the resin film303, a N₂ gas, an O₂ gas and a H₂ gas were supplied as the processinggas at the flow rates of 200 mL/min (sccm), 18 mL/min (sccm) and 100mL/min (sccm), respectively. Further, a CO gas capable of increasing thefilm ingredients in the etching atmosphere was supplied as theadditional gas toward the region outside the outer edge of the waferthrough the third gas diffusion space 40 c at the flow rate of 40 mL/min(sccm). The pressure in the chamber was set to 2.3 Pa (17 mTorr), andthe high frequency power was set to 300 W. When plasma-etching theanti-reflection film 304, the processing gas was supplied through thethird gas diffusion space 40 c.

As a result, when etching the polyvinyl alcohol-based resin film 303,the critical dimension in the outermost circumferential portion of thewafer was corrected with the help of the reaction of the CO gas used asthe additional gas. Thus, it was possible to perform the etchingoperation with increased uniformity. Despite the fact that theadditional gas was not supplied during the etching of theanti-reflection film 304, neither abnormal electric discharge nordeposit was generated because the processing gas was injected from thethird gas diffusion space 40 c for use in supplying the additional gas.

The present invention is not limited to embodiment described above andvarious modification may be made. For example, the processing gas may besplit to flow toward three or more regions, although the processing gasis split into two to flow toward the first gas inlet portion 51corresponding to the central region of the wafer and the second gasinlet portion 52 corresponding to the peripheral region of the wafer inthe above embodiment. Further, the gas inlet portions are notnecessarily arranged in a concentric pattern. In addition, although theprocessing gas and the additional gas are introduced through the showerhead 16 in the above embodiment, they may be introduced through, e.g.,gas lines, in place of the shower head.

While the above embodiment is directed to plasma etching, the presentinvention is not limited thereto. Alternatively, the present inventionmay be applied to other plasma processing such as plasma CVD and thelike or non-plasma processing such as thermal CVD and the like.

While the semiconductor wafer is used as the target substrate in theabove embodiment, the present invention is not limited thereto. Othersubstrates such as a substrate for flat panel displays and the like maybe used as the target substrate.

What is claimed is:
 1. A gas supply device for supplying a gas into aprocessing chamber in which a target substrate is arranged, comprising:a gas introduction member including therein a gas diffusion space,through which the gas is introduced into the processing chamber, the gasdiffusion space having a first gas diffusion space positioned at acentral region of the gas introduction member, a second as diffusionspace positioned outside the first as diffusion space, and a third gasdiffusion space positioned outside the second gas diffusion space; aprocessing gas supply unit configured to supply a processing gas intothe gas introduction member, the processing gas being used to processthe target substrate; a processing gas supply path, connected to theprocessing gas supply unit, through which the processing gas flows fromthe processing gas supply unit; branch paths branched off from theprocessing gas supply path and connected to the gas introduction member,the branch paths having a first branch path configured to supply onlythe processing gas to the first gas diffusion space and a second branchpath configured to supply only the processing gas to the second gasdiffusion space; an additional gas supply unit configured to supply anadditional gas into the gas introduction member, the additional gasbeing used to adjust processing characteristics of the processing gas;an additional gas supply path separate from the branch paths, andconnected to the additional gas supply unit and the gas introductionmember, through which the additional gas flows from the additional gassupply unit to the third gas diffusion space; a branch flow controllerhaving a first flow rate control valve and a first pressure sensor inthe first branch path, and having a second flow rate control valve and asecond pressure sensor in the second branch path; a bypass passageconfigured to connect the second branch path to the additional gassupply path; and a bypass valve arranged at at least one of the bypasspassage and the additional gas supply path, wherein, in a case where theadditional gas is introduced into the processing chamber, the bypassvalve is configured to disconnect the third gas diffusion space from thebypass passage so that the additional gas is supplied into the third gasdiffusion space, and, in a case where the additional gas is notintroduced into the processing chamber, the bypass valve is configuredto disconnect the third gas diffusion space from the additional gassupply unit so that the processing gas is supplied into the third gasdiffusion space through the bypass passage, and wherein the branch flowcontroller is configured to control a ratio of a flow rate of theprocessing gas supplied through the first branch path to that of theprocessing gas supplied through the second branch path by adjusting anopening degree of each of the first and the second flow rate controlvalves based on the first and the second pressure sensors.
 2. The gassupply device of claim 1, wherein the gas introduction member includesgas inlet portions having a first gas inlet portion formed with thefirst gas diffusion space, a second gas inlet portion formed with thesecond gas diffusion space, and a third gas inlet portion formed withthe third gas diffusion space, and wherein the gas inlet portions areprovided in a concentric pattern.
 3. The gas supply device of claim 1,wherein the gas introduction member constitutes a shower head having gasinjection holes formed at a bottom thereof.
 4. A gas supply device forsupplying a gas into a processing chamber in which a target substrate isarranged, comprising: a gas introduction member configured to introducethe gas into the processing chamber; one or more gas inlet portionsprovided at a bottom portion of the gas introduction member, the gasinlet portions having a first gas inlet portion positioned at a centralregion of the gas introduction member, a second gas inlet portionpositioned outside the first gas inlet portion, and a third gas inletportion positioned outside the second gas inlet portion; a processinggas supply unit configured to supply a processing gas to the gasintroduction member, the processing gas being used to process the targetsubstrate; a processing gas supply path, connected to the processing gassupply unit, through which only the processing gas is supplied from theprocessing gas supply unit to the one or more gas inlet portions; branchpaths branched off from the processing gas supply path and connected tothe gas introduction member, the branch paths having a first branch pathconfigured to supply only the processing gas to the first gas inletportion, and a second branch path configured to supply only theprocessing gas to the second gas inlet portion; an additional gas supplyunit configured to supply an additional gas to the gas introductionmember, the additional gas being used to adjust processingcharacteristics of the processing gas; an additional gas supply path,separate from the processing gas supply path, and connected to theadditional gas supply unit and the gas introduction member, throughwhich the additional gas is supplied from the additional gas supply unitto the third gas inlet portion; a branch flow controller having a firstflow rate control valve and a first pressure sensor in the first branchpath, and having a second flow rate control valve and a second pressuresensor in the second branch path; a bypass passage configured to connectthe second branch path to the additional gas supply path; and a bypassvalve arranged at at least one of the bypass passage and the additionalgas supply path, wherein, in a case where the additional gas isintroduced into the processing chamber, the bypass valve is configuredto disconnect the gas introduction member from the bypass passage sothat the additional gas is supplied to the third gas inlet portion, and,in a case where the additional gas in not introduced into the processingchamber, the bypass valve is configured to disconnect the gasintroduction member from the additional gas supply unit so that theprocessing gas is supplied into the third gas inlet portion through thebypass passage, and wherein the branch flow controller is configured tocontrol a ratio of a flow rate of the processing gas supplied throughthe first branch path to that of the processing gas supplied through thesecond branch path by adjusting an opening degree of each of the firstand the second flow rate control valves based on the first and thesecond pressure sensors.
 5. The gas supply device of claim 4, whereinthe gas introduction member includes therein a gas diffusion space, andwherein the gas introduction member constitutes a shower head having gasinjection holes formed at a bottom thereof, the gas injection holescorresponding to the gas diffusion space.
 6. The gas supply device ofclaim 1, wherein the additional gas differs from the processing gas. 7.The gas supply device of claim 1, wherein the processing gas comprisesplural gases, the additional gas differing from the gases or being apart of the gases which form the processing gas.
 8. A substrateprocessing apparatus comprising: a processing chamber in which a targetsubstrate is arranged; and a gas supply device configured to supply agas into the processing chamber, wherein a processing gas used toprocess the target substrate is supplied from the gas supply device intothe processing chamber to perform a specific processing onto the targetsubstrate, the gas supply device including a gas introduction memberincluding therein a gas diffusion space, through which the gas isintroduced into the processing chamber, the gas diffusion space having afirst gas diffusion space positioned at a central region of the gasintroduction member, a second gas diffusion space positioned outside thefirst gas diffusion space, and a third as diffusion space positionedoutside the second as diffusion space; a processing gas supply unitconfigured to supply the processing gas into the gas introductionmember; a processing gas supply path, connected to the processing assupply unit, through which the processing gas flows from the processinggas supply unit; branch paths branched off from the processing gassupply path and connected to the gas introduction member, the branchpaths having a first branch path configured to supply only theprocessing gas to the first gas diffusion space, and a second branchpath configured to supply only the processing gas to the second gasdiffusion space; an additional gas supply unit configured to supply anadditional gas into the gas introduction member, the additional gasbeing used in adjusting processing characteristics of the processinggas; an additional gas supply path separate from the branch paths andconnected to the additional gas supply unit and the gas introductionmember, through which the additional gas flows from the additional gassupply unit to the third gas diffusion space; a branch flow controllerhaving a first flow rate control valve and a first pressure sensor inthe first branch path, and having a second flow rate control valve and asecond pressure sensor in the second branch path; a bypass passageconfigured to connect the second branch path to the additional gassupply path; and a bypass valve arranged at at least one of the bypasspassage and the additional gas supply path, wherein, in a case where theadditional gas is introduced into the processing chamber, the bypassvalve is configured to disconnect the third gas diffusion space thebypass passage so that the additional gas is supplied into the third gasdiffusion space, and, in a case where the additional gas is notintroduced into the processing chamber, the bypass valve is configuredto disconnect the third gas diffusion space from the additional gassupply unit so that the processing gas is supplied into the third gasdiffusion space through the bypass passage, and wherein the branch flowcontroller is configured to control a ratio of a flow rate of theprocessing gas supplied through the first branch path to that of theprocessing gas supplied through the second branch path by adjusting anopening degree of each of the first and the second flow rate controlvalves based on the first and the second pressure sensors.
 9. Asubstrate processing apparatus comprising: a processing chamber in whicha target substrate is arranged; and a gas supply device configured tosupply a gas into the processing chamber, wherein a processing gas usedto process the target substrate is supplied from the gas supply deviceinto the processing chamber to perform a specific processing onto thetarget substrate, the gas supply device including a gas introductionmember configured to introduce the gas into the processing chamber; oneor more gas inlet portions provided at a bottom portion of the gasintroduction member, the gas inlet portions having a first gas inletportion positioned at a central region of the gas introduction member, asecond gas inlet portion positioned outside the first gas inlet portion,and a third gas inlet portion positioned outside the second gas inletportion; a processing gas supply unit configured to only supply theprocessing gas to the gas introduction member, the processing gas beingused to process the target substrate; a processing gas supply path,connected to the processing gas supply unit, through which only theprocessing gas is supplied from the processing gas supply unit to theone or more gas inlet portions; branch paths branched off from theprocessing gas supply path and connected to the gas introduction member,the branch paths having a first branch path configured to supply onlythe processing gas to the first gas inlet portion, and a second branchpath configured to supply only the processing gas to the second gasinlet portion; an additional gas supply unit configured to supply anadditional gas to the gas introduction member, the additional gas beingused in adjusting processing characteristics of the processing gas; anadditional gas supply path, separate from the processing gas supplypath, and connected to the additional gas supply unit and the gasintroduction member, through which the additional gas is supplied fromthe additional gas supply unit to the third gas inlet portion; and abranch flow controller having a first flow rate control valve and afirst pressure sensor branch path, and having a second flow rate controlvalve and a second pressure sensor in the second branch path; a bypasspassage configured to connect the second branch path to the additionalgas supply path; and a bypass valve arranged at at least one of thepassage and the additional gas supply path, wherein, in a case where theadditional gas is introduced into the processing chamber, the bypassvalve is configured to disconnect the gas introduction member from thebypass passage so that the additional gas is supplied to the third gasinlet portion, and, in a case where the additional gas is not introducedinto the processing chamber, the bypass valve is configured todisconnect the gas introduction member from the additional gas supplyunit so that the processing gas is supplied into the third gas inletthrough the bypass passage, and wherein the branch flow controller isconfigured to control a ratio of a flow rate of the processing gassupplied through the first branch path to that of the processing gassupplied through the second branch path by adjusting an opening degreeof each of the first and the second flow rate control valves based onthe first and the second pressure sensors.
 10. The gas supply device ofclaim 1, wherein the gas introduction member includes a first and asecond annular partition wall member, and wherein the gas diffusionspace is divided into the first and the second gas diffusion space bythe first annular partition wall member, and is divided into the secondand the third gas diffusion space by the second annular partition wallmember.
 11. The gas supply device of claim 5, wherein the gas diffusionspace includes a first gas diffusion space positioned at a centralregion of the gas introduction member, a second gas diffusion spacepositioned outside the first gas diffusion space, and a third gasdiffusion space positioned outside the second gas diffusion space,wherein the gas introduction member includes a first and a secondannular partition wall member, and wherein the gas diffusion space isdivided into a first gas diffusion space and a second gas diffusionspace by the first annular partition wall member, and is divided intothe second gas diffusion space and a third gas diffusion space by thesecond annular partition wall member.
 12. The substrate processingapparatus of claim 8, wherein the gas introduction member includes afirst and a second annular partition wall member, and wherein the gasdiffusion space is divided into the first and the second gas diffusionspace by the first annular partition wall member, and is divided intothe second and the third gas diffusion space by the second annularpartition wall member.
 13. The substrate processing apparatus of claim9, wherein the gas introduction member includes a gas diffusion spacehaving a first gas diffusion space positioned at a central region of thegas introduction member, a second gas diffusion space positioned outsidethe first gas diffusion space, and a third gas diffusion spacepositioned outside the second gas diffusion space, wherein the gasintroduction member includes a first and a second annular partition wallmember, and wherein the gas diffusion space is divided into the firstand the second gas diffusion space by the first annular partition wallmember, and is divided into the second and the third gas diffusion spaceby the second annular partition wall member.
 14. A gas supply device forsupplying a gas into a processing chamber in which a target substrate isarranged, comprising: a processing gas supply unit configured to supplya processing gas into the processing chamber; a processing gas supplypath, connected to the processing gas supply unit, through which theprocessing gas flows from the processing gas supply unit; branch pathsbranched off from the processing gas supply path and connected to theprocessing chamber, the branch paths having a first branch path and asecond branch path; an additional gas supply unit configured to supplyan additional gas into the processing chamber; an additional gas supplypath connected to the additional gas supply unit and connected to theprocessing chamber, through which the additional gas flows from theadditional gas supply unit; a branch flow controller having a first flowrate control valve and a first pressure sensor in the first branch path,and having a second flow rate control valve and a second pressure sensorin the second branch path; a bypass passage configured to connect thesecond branch path to the additional gas supply path; and a bypass valvearranged at at least one of the bypass passage and the additional gassupply path, wherein, in a case where the additional gas is introducedinto the processing chamber, the bypass valve is configured todisconnect the processing chamber from the bypass passage so that theadditional gas is supplied into the processing chamber through theadditional gas supply path, and, in a case where the additional gas isnot introduced into the processing chamber, the bypass valve isconfigured to disconnect the processing chamber from the additional gassupply unit so that the processing gas is supplied into the processingchamber through the bypass passage, and wherein the branch flowcontroller is configured to control a ratio of a flow rate of theprocessing gas supplied through the first branch path to that of theprocessing gas supplied through the second branch path by adjusting anopening degree of each of the first and the second flow rate controlvalve based on the first and the second pressure sensor.
 15. The gassupply device of claim 1, wherein the bypass valve is arranged at ajunction point of the bypass passage and the additional gas supply path.16. The gas supply device of claim 4, wherein the bypass valve isarranged at a junction point of the bypass passage and the additionalgas supply path.
 17. The gas supply device of claim 5, wherein thebypass valve is arranged at a junction point of the bypass passage andthe additional gas supply path.
 18. The substrate processing apparatusof claim 8, wherein the bypass valve is arranged at a junction point ofthe bypass passage and the additional gas supply path.
 19. The substrateprocessing apparatus of claim 9, wherein the bypass valve is arranged ata junction point of the bypass passage and the additional gas supplypath.
 20. The gas supply device of claim 14, wherein the bypass valve isarranged at a junction point of the bypass passage and the additionalgas supply path.